A flexible retaining ring positioned within a groove of a workpiece effectively provides an abutment preventing axial displacements of parts mounted on the workpiece. In the assembly operations, initially, the flexible retaining ring is typically placed in the vicinity of the corresponding groove of the workpiece and then shifted to a position in which the retaining ring embraces the groove along its exterior surface. The retaining ring is typically installed by pushing its opening against the groove, causing the ring ends to separate. After the expanded ring engages the groove, the ends of the ring snap back to secure the ring in place. A properly installed retaining ring locks itself against the corresponding groove with a holding power enabling the ring to resist forces directed along a longitudinal axis of the workpiece as well as impact and shock forces, so as to prevent undesirable shifting of the ring and parts mounted on the workpiece.
Rapid development of industries utilizing assembly operations employing the spring retaining rings has created a continuous demand for progressively greater speed of the ring's installing operations as well as increased reliability of their engagement with the workpiece. To satisfy these demands, devices such as fluid driven applicators forcibly inserting the retaining rings into grooves of workpieces, could be employed.
In using such applicators, an important task is to deliver the retaining ring to the workpiece in such a manner that an opening or gap of the ring faces and is aligned with a corresponding groove. However, if the opening in the ring is not properly aligned with the corresponding groove, upon application of forces the ring could be smashed against a workpiece clogging the applicator as well as damaging the groove. Yet another problem with rings which are not properly aligned with corresponding grooves, is that a ring can be installed only partially within the groove and partially outside the groove. If not detected, this condition will yield a defective workpiece assembly and ultimately could lead to a more serious problem for the final product. Defects of this nature materially reduce the yield of good devices and introduce defects into the product stream. Such problems are particularly acute with those assemblies utilizing relatively thin retaining rings installed into narrow grooves and utilizing workpieces having small distances between adjacent grooves.
Various approaches have been taken toward resolving the above-mentioned problems. For example, U.S. Pat. No. 4,667,399 to Berliner provides a specially designed spring retaining ring and a power gun for its installation. In order to prevent rotation of the ring during its motion within the power gun and to provide a proper alignment between the opening of the ring and the corresponding groove of the workpiece, the ring of '399 patent is formed having two flat portions on each side thereof. Such flat portions engage sides of a delivery passageway of the power gun and prevent the ring from undesired radial movements. However, the circumferential exterior shape of the retaining rings is widely accepted in industry. Therefore, the application for the rings having flats on their sides is substantially limited. Furthermore, manufacture of rings having such flats is often more expensive than that of the rings having a circumferential or curved exterior. The apparatus of '399 patent contains two movable groove locators which are complicated in manufacturing and maintenance and do not effectively serve their purpose of guiding a ring prior to its installation within the groove.
U.S. Pat. No. 4,550,485 to Killian and U.S. Pat. No. 4,592,122 to Sikula also disclose devices for installing retaining rings into a groove of a workpiece utilizing complicated, movable groove locators which are often jammed during operation of the device, expensive in manufacture and maintenance, and do not prevent a ring turning within the applicator.
Despite the substantial time and effort devoted heretofore to the problems associated with installing retaining rings into grooves of workpieces, there have still been substantial, unmet needs for improvements in such equipment. Thus, there has been a considerable need for a universal, simple, inexpensive and reliable apparatus which is capable of providing a proper alignment during the inserting operation between an opening of a retaining ring and a corresponding groove as well as assuring ultimate reliable engagement between the ring and the workpiece. There is a need for the apparatus which should not require constant and often expensive maintenance.